Re: [PATCH v2] ACPI: EC: s2idle: Avoid premature returns from acpi_s2idle_wake()

[Chris Chiu <chiu@endlessm.com>]

On Sat, May 9, 2020 at 4:44 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> If the EC GPE status is not set after checking all of the other GPEs,
> acpi_s2idle_wake() returns 'false', to indicate that the SCI event
> that has just triggered is not a system wakeup one, but it does that
> without canceling the pending wakeup and re-arming the SCI for system
> wakeup which is a mistake, because it may cause s2idle_loop() to busy
> spin until the next valid wakeup event.  [If that happens, the first
> spurious wakeup is still pending after acpi_s2idle_wake() has
> returned, so s2idle_enter() does nothing, acpi_s2idle_wake()
> is called again and it sees that the SCI has triggered, but no GPEs
> are active, so 'false' is returned again, and so on.]
>
> Fix that by moving all of the GPE checking logic from
> acpi_s2idle_wake() to acpi_ec_dispatch_gpe() and making the
> latter return 'true' only if a non-EC GPE has triggered and
> 'false' otherwise, which will cause acpi_s2idle_wake() to
> cancel the pending SCI wakeup and re-arm the SCI for system
> wakeup regardless of the EC GPE status.
>
> This also addresses a lockup observed on an Elitegroup EF20EA laptop
> after attempting to wake it up from suspend-to-idle by a key press.
>
> Fixes: d5406284ff80 ("ACPI: PM: s2idle: Refine active GPEs check")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=207603
> Reported-by: Todd Brandt <todd.e.brandt@linux.intel.com>
> Fixes: fdde0ff8590b ("ACPI: PM: s2idle: Prevent spurious SCIs from waking up the system")
> Link: https://lore.kernel.org/linux-acpi/CAB4CAwdqo7=MvyG_PE+PGVfeA17AHF5i5JucgaKqqMX6mjArbQ@mail.gmail.com/
> Reported-by: Chris Chiu <chiu@endlessm.com>
> Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
Tested-by: Chris Chiu <chiu@endlessm.com>
>
> -> v2:
>    * Improve the changelog and add more tags.
>
> ---
>  drivers/acpi/ec.c       |   24 ++++++++++++++++--------
>  drivers/acpi/internal.h |    1 -
>  drivers/acpi/sleep.c    |   14 ++------------
>  3 files changed, 18 insertions(+), 21 deletions(-)
>
> Index: linux-pm/drivers/acpi/sleep.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/sleep.c
> +++ linux-pm/drivers/acpi/sleep.c
> @@ -1013,21 +1013,11 @@ static bool acpi_s2idle_wake(void)
>                 if (acpi_check_wakeup_handlers())
>                         return true;
>
> -               /*
> -                * If the status bit is set for any enabled GPE other than the
> -                * EC one, the wakeup is regarded as a genuine one.
> -                */
> -               if (acpi_ec_other_gpes_active())
> +               /* Check non-EC GPE wakeups and dispatch the EC GPE. */
> +               if (acpi_ec_dispatch_gpe())
>                         return true;
>
>                 /*
> -                * If the EC GPE status bit has not been set, the wakeup is
> -                * regarded as a spurious one.
> -                */
> -               if (!acpi_ec_dispatch_gpe())
> -                       return false;
> -
> -               /*
>                  * Cancel the wakeup and process all pending events in case
>                  * there are any wakeup ones in there.
>                  *
> Index: linux-pm/drivers/acpi/ec.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/ec.c
> +++ linux-pm/drivers/acpi/ec.c
> @@ -1994,23 +1994,31 @@ void acpi_ec_set_gpe_wake_mask(u8 action
>                 acpi_set_gpe_wake_mask(NULL, first_ec->gpe, action);
>  }
>
> -bool acpi_ec_other_gpes_active(void)
> -{
> -       return acpi_any_gpe_status_set(first_ec ? first_ec->gpe : U32_MAX);
> -}
> -
>  bool acpi_ec_dispatch_gpe(void)
>  {
>         u32 ret;
>
>         if (!first_ec)
> +               return acpi_any_gpe_status_set(U32_MAX);
> +
> +       /*
> +        * Report wakeup if the status bit is set for any enabled GPE other
> +        * than the EC one.
> +        */
> +       if (acpi_any_gpe_status_set(first_ec->gpe))
> +               return true;
> +
> +       if (ec_no_wakeup)
>                 return false;
>
> +       /*
> +        * Dispatch the EC GPE in-band, but do not report wakeup in any case
> +        * to allow the caller to process events properly after that.
> +        */
>         ret = acpi_dispatch_gpe(NULL, first_ec->gpe);
> -       if (ret == ACPI_INTERRUPT_HANDLED) {
> +       if (ret == ACPI_INTERRUPT_HANDLED)
>                 pm_pr_dbg("EC GPE dispatched\n");
> -               return true;
> -       }
> +
>         return false;
>  }
>  #endif /* CONFIG_PM_SLEEP */
> Index: linux-pm/drivers/acpi/internal.h
> ===================================================================
> --- linux-pm.orig/drivers/acpi/internal.h
> +++ linux-pm/drivers/acpi/internal.h
> @@ -202,7 +202,6 @@ void acpi_ec_remove_query_handler(struct
>
>  #ifdef CONFIG_PM_SLEEP
>  void acpi_ec_flush_work(void);
> -bool acpi_ec_other_gpes_active(void);
>  bool acpi_ec_dispatch_gpe(void);
>  #endif
>
>
>
>